Structure, antioxidant and immunomodulatory activity of a polysaccharide extracted from Sacha inchi seeds

In this study, a novel water-soluble polysaccharide (PVLP-1) was extracted and purified from Sacha inchi (Plukenetia volubilis L.) seeds and the structure, antioxidant and immunomodulatory activity of PVLP-1 were investigated. PVLP-1 (144 kDa) consisted of glucose (69.76%), mannose (14.86%), arabinose (10.53%), galactose (2.42%), ribose (1.23%), rhamnose (0.27%) and xylose (0.93%). PVLP-1 displayed characteristic polysaccharide bands in Fourier transform NMR spectra and infrared. The primary structure of PVLP-1 was a heteropolysaccharide with a backbone of (1 → 6)-linked glucose, sidechains of (1 → 4)-linked mannose, (1 → 4)-linked glucose and (1 → 3, 6)-linked mannose and a residue unit of →1)-linked arabinose as revealed the methylation analysis. PVLP-1 possessed good water-holding capacity (WHC), oil-holding capacity (OHC) and antioxidant capacities. Besides, PVLP-1 induced the proliferation of RAW264.7 cell and enhanced the expression of inflammatory cytokines IL-6, TNF-alpha(TNF-α) and IL-1 beta (IL-1β). The present study indicated that PVLP-1 possessed immune-enhancing bioactivities and could be functional food or adjuvant drug to improve biological immunity of immunodeficiency diseases and hypoimmunity.